Internal combustion engines have been known for many years and are used in airplanes, automobiles, and other vehicles, as well as for some industrial purposes. The internal combustion engines of today were developed at a time when fuel supplies were believed to be infinitely plentiful. As a result, these engines operate in a manner which is now considered inefficient and wasteful of limited fuel resources.
A great deal of time and research is presently being devoted to improving the efficiency and decreasing the fuel consumption of internal combustion engines.
The gasoline powered engine typically used today has been designed to require high-octane gasoline. A gasoline rich mixture of gasoline and air is ignited within the cylinder by a spark produced by an electrically operated spark plug. However, only the mixture in the immediate vicinity of the spark ignites, and a flame front moves out from the spark plug. As the flame front proceeds, it compresses the unburned mixture. If the octane of the unburned mixture is not sufficiently high, the compressed mixture may detonate causing a loud knocking noise and reducing the efficiency of the engine. To eliminate the detonation-engendering flame front a high octane fuel is required, but such fuel is costly to refine and lesser amounts are produced per barrel of crude oil than lower octane fuels. Because of these problems research has proceeded in an effort to develop internal combustion engines that operate more efficiently and more cleanly on lower octane fuels.
A development that is still in the experimental stages is the plasma-jet ignition developed by Professor A. K. Oppenheim at the University of California at Berkeley which is described in the September 1979 issue of Popular Science beginning at page 74. The plasma-jet ignition utilizes an ionized plasma which is injected into the combustion chamber. Initially, the ion cloud penetrates into the chamber and expands. As it expands very little combustion occurs. When the ion cloud has expanded sufficiently, combustion proceeds rapidly from many ignition points rather than from a single spark because the plasma comprises hot, highly charged particles. In this manner, almost the entire charge is ignited and burns smoothly. There is no flame front which propagates from a single spark. Thus, the plasma-jet ignition permits the use of lower octane fuels and much leaner mixtures of fuel and air than internal combustion engines using conventional spark plug ignition. However, the plasma-jet ignition is not yet commercially feasible for operating an engine.
In the same article of the September 1979 issue of Popular Science, another recent development is described which is called the controlled-combustion system. Combustion is initiated in this system by simultaneous fuel injection and spark ignition. By injecting the fuel into the vicinity of the spark, the air within the combustion chamber is caused to swirl about the chamber. The products of combustion, the flame front, and the combustible mixture are swept downstream and away from the spark by the air swirl. In this manner, cylinder pressure builds at a controlled rate. The spark is discontinued, but fuel injection continues to feed the swirling flame front until the maximum power is reached. The fuel injection is then discontinued and the intensity of the flame front fades, but combustion continues until all of the fuel is consumed. This system has no octane requirements and operates efficiently and cleanly on a leaner fuel/air mixture than conventional spark plug ignited internal combustion engines require.
Lasers or other sources of amplified light have been used in conjunction with ignition systems. The beam of amplified light produced by a laser has been utilized as part of various timing devices which actuate a mechanism which produces ignition sparks. Similar to contacts in a distributor used in connection with a conventional ignition system, light pulses are used to provide timed contacts with a device that senses the light pulse and provides an electrical signal for initiating each spark. However, the light pulse does not contact the fuel/air mixture which is ignited.
In some solid fuel rockets, lasers have been used to ignite a solid propellant igniter or to simultaneously ignite several such igniters. The amplified light is directed at the igniter with an intensity sufficient to ignite the solid propellant possessed by the igniter. The igniter in turn then ignites the solid fuel within the rocket at a predetermined rate.
A high intensity beam of light from a ruby laser has been used to ignite a very lean 1:1000 oil to air mixture in a boiler. The beam has energy density sufficient to maintain combustion in the oil/air mixture volume after the laser impulse terminates. Each laser impulse occurs only when needed to initiate combustion for maintenance of the desired boiler temperature.
In each of the mentioned fuel ignition systems, and for that matter, in every ignition system, it is critical that the timing and rate of ignition be controllable or, at least, predictable so that the energy released by the combustion of the fuel may be harnessed in an efficient manner. It is also important to the preservation of our environment and conservation of our resources that the fuel burn cleanly and as completely as possible. Accordingly, an engine that operates efficiently on a leaner mixture of fuel and air than usual is desirable because it conserves fuel and reduces harmful emissions.
The amplified radiation igniter system of the present invention eliminates many of the problems presented by the currently used igniter systems and achieves many of the results desired in improving the operation of internal combustion engines.
Accordingly, it is an object of this invention to provide an igniter system that initiates a cleaner and more efficient combustion than conventional spark plug ignition systems.
Another object of the present invention is to provide an amplified radiation igniter system which ignites the fuel within the combustion chamber at many points along the path of the radiation almost instantaneously (i.e., at or near the speed of light).
A further object of the invention is to provide an ignition system that operates efficiently when the engine is provided with a mixture of fuel to air that is leaner in fuel than mixtures required by conventional spark plug ignition systems.
Still another object of the present invention is to initiate combustion of a fuel/air mixture within the combustion chamber of an internal combustion engine with amplified radiation provided by a laser or maser.
Another object of the present invention is to provide combustion initiating radiation pulses to the combustion chamber of an internal combustion engine via flexible radiation transmitting fibers.
Other objects and advantages of the invention will become apparent upon the reading of the following detailed description and appended claims, and upon reference to the accompanying drawings.